The prosecutors on Thursday asked U.S. District Judge Herbert J. Hutton to disqualify Santaguida from continuing to act as a defense attorney for reputed mob boss Joseph "Skinny Joey" Merlino. Nor should Santaguida be allowed to defend any of Merlino's pals who await trial with Merlino on murder conspiracy and other racketeering charges, the prosecutors said. They cited "actual conflicts of interest" that Santaguida's mob associations allegedly entail.

Santaguida could be indicted for a felony and, at the very least, find his license to practice law in jeopardy, the federal prosecutors said.

Santaguida couldn't be reached for comment yesterday.

But in court papers, authorities allege that Santaguida, in 1995, asked former mob boss Ralph Natale, now a key government witness, to collect a $35,000 to $40,000 debt owed Santaguida's son by a real estate developer with mob ties.

The prosecutors also contend Santaguida urged Natale to meet with a Merlino associate who "wanted to take control of a union. . .for mob financial benefit."

About three months ago, Gaetano "Horsehead" Scafidi, 35, a former mob soldier now cooperating with authorities, told the FBI that Santaguida claimed Merlino "was all screwed up." He allegedly told Scafidi that Joseph Ligambi had assumed the reins as boss of the Philadelphia mob.All this shows that Santaguida was more than just a defense attorney for mobsters, the prosecutors argue.

"According to Natale, Santaguida saw him almost weekly at the Garden State Race Track during the period in question and frequently, Santaguida asked Natale how Merlino was regarded by the New York mob families," the prosecutors told the judge.

"Moreover, Santaguida expressed great delight when Natale predicted that Merlino would probably become the boss upon Natale's retirement."

The prosecutors hope to convince a jury that Natale was "leader of a violent organization that regularly collected money through explicit threats. . .and the use of actual violence."

The evidence will show that "Santaguida knew exactly who and what Natale was," prosecutors said in the court papers.